Proximity Interactome Map of the Vac14-Fig4 Complex Using BioID

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• The PIKfyve-Vac14-Fig4 complex is essential for endosomal maturation and homeostasis.
• Regulation and protein interactions of this complex are not well understood.

Purpose of the Study:

• To comprehensively map the interactome of Vac14 and Fig4 using proximity-dependent biotin labeling (BioID).
• To identify novel cellular pathways and protein interactions associated with the PIKfyve-Vac14-Fig4 complex.

Main Methods:

• Proximity-dependent biotin labeling (BioID) to screen interactomes of Vac14 and Fig4.
• Network analysis to identify enriched pathways.
• Proximity ligation assays (PLA) to validate specific protein interactions.

Main Results:

• Identified 89 high-confidence shared protein interactors for Vac14 and Fig4.
• Network analysis revealed involvement in vesicular organization, PI3K/Akt signaling, cell cycle, and mitochondrial regulation.
• Discovered interactions with coatomer complex I (COPI) subunits, including COPB1, and Arf1.

Conclusions:

• The Vac14-Fig4 interactome is broader than previously known, implicating the PIKfyve-Vac14-Fig4 complex in diverse cellular processes.
• Preliminary evidence suggests a novel interaction between Vac14 and COPI, potentially linking Golgi and endosomal dynamics.